Summer irrigation, grazing and seed addition differentially influence community composition in an invaded serpentine grassland

Published source details Funk J.L., Hoffacker M.K. & Matzek V. (2015) Summer irrigation, grazing and seed addition differentially influence community composition in an invaded serpentine grassland. Restoration Ecology, 23, 122-130.
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This study is summarised as evidence for the following.

	Action	Category
	Soil: Exclude grazers Action Link
	Graze with livestock after seeding/planting Action Link
	Sow grass seeds Action Link
	Other biodiversity: Exclude grazers Action Link

Soil: Exclude grazers

A replicated, controlled study in 2012–2013 in grasslands in central California, USA, found less soil nitrogen in plots with cattle excluded, compared to grazed plots. Nutrients: Less soil nitrogen was found in ungrazed plots, compared to grazed plots (14–16 vs 17–24 mg NH₄ and NO₃ combined). Methods: Sixty 1 x 1 m plots were established in summer 2012: half in an area grazed at 0.25 cow-calf pairs/ha, and half in an area fenced in 2012 to exclude cattle. Soil cores (5 cm diameter, 0–10 cm depth) were collected in April 2013.
Graze with livestock after seeding/planting

A replicated, controlled study in 2012–2013 in a serpentine grassland in California, USA (Funk et al. 2015) found that grazing with cattle after sowing grass seeds led to a greater number, but lower cover, of native plant species compared to not grazing after sowing. Plots grazed with cattle after sowing seeds had on average more native plant species (10 species/plot) than plots not grazed after sowing (9 species/plot). However, grazed plots had lower native plant species cover (63%) than ungrazed plots (77%). The cover of non-native invasive species did not differ significantly between grazed (20%) and ungrazed plots (29%). In November 2012, twenty 1 x 1 m irrigated plots were sown with seeds of three native grass species. Half of the plots were grazed by cattle (0.25 cow-calf pairs/ha) from November 2012 to May 2013, while the other half were fenced and not grazed. Vegetation cover was estimated in March and April 2013 using a 0.25 × 0.25 m quadrat placed in each plot.

(Summarised by: Anna Berthinussen)
Sow grass seeds

A replicated, controlled study in 2012–2013 in a serpentine grassland in California, USA (Funk et al. 2015) found that sowing grass seeds did not alter native plant species richness or the cover of native or non-native invasive plant species. Average numbers of native plant species did not differ significantly between plots sown with grass seeds and plots not sown with seeds (both 9–10 species/plot). The same was true for the cover of native plants (sown: 63–77%; unsown: 54–71%) and the cover of non-native invasive plants (sown: 20–29%; unsown: 18–26%). In November 2012, twenty 1 x 1 m plots were sown with 20 seeds of three native grass species (collected onsite 2–3 months prior), while 20 plots were left unsown. All plots were irrigated for 21 days in August 2012. Half of the plots for each treatment were grazed by cattle. Vegetation cover was estimated in March and April 2013 using a 0.25 × 0.25 m quadrat placed in each plot.

(Summarised by: Anna Berthinussen)
Other biodiversity: Exclude grazers

A replicated controlled study in 2012–2013 in grasslands in central California, USA, found fewer species but higher cover of native plants in plots not grazed by cattle, compared to grazed plots. Cover of invasive species and the emergence of native seedlings did not differ between grazed and ungrazed plots. Plants: Fewer species of native plants were found in plots from which cattle were excluded, compared to grazed plots (8.5–8.8 vs 10.2 species/m²). The same number of native seedlings emerged in grazed and ungrazed plots (0–1.1 seedlings/m²). Cover of native plants was higher in plots from which cattle were excluded, compared to grazed plots (72–83% vs 55–65% cover). Cover of invasive species did not differ between grazed and ungrazed plots (18–29% cover). Methods: Sixty 1 x 1 m plots were established in summer 2012: half in an area grazed at 0.25 cow-calf pairs/ha and half in an area fenced in 2012 to exclude cattle. Plant species and cover was assessed once in 2013.